CSEC Industrial Technology Paper 2 May/June 2017 - Free CXC Past Paper with Answers

Draw the electrical/electronic symbols for EACH of the following components. (i) Fuse (ii) Diode (iii) Fluorescent lamp (iv) Inverter (v) RS flip flop (vi) Earth

Figure 2 shows a schematic diagram of a filament lamp controlled by a single-pole switch connected to an alternating current supply.

Draw a wiring diagram for the schematic diagram in Figure 2 to construct the filament lamp circuit using twin core flat PVC cable with earth conductor and a four-terminal all-insulated joint box.

Figure 3 shows a block diagram of a personal computer.

Briefly outline the function of any TWO of the blocks in the block diagram.

List the names of THREE types of single-phase AC electrical motors used to construct electrical and electronic appliances and equipment.

List THREE types of losses that are produced in the operation of an alternating current transformer.

A 120 V to 12 V bell transformer operates at 100% efficiency and supplies a 12 V, 6 W alarm bell. The transformer is wound with 400 turns of the primary winding. Calculate the

secondary current

primary current.

Figure 4 shows the schematic drawing of a three-phase direct on line motor starter.

Outline the circuit relationships that are required to connect remote stop and start pushbuttons to the existing start and stop pushbuttons on the motor starter.

Outline THREE changes that can be made in the connections of a three-phase AC motor to produce a change in the direction of rotation of the armature of the machine.

Define EACH of the following terms:

Fusing current

Fusing factor

Illumination

Luminous flux

Primary cell

Secondary cell

A 3000 cd light source is suspended 4 m above a plain surface. Calculate the illumination

on the plain surface directly below the lamp

on the plain surface 4 m from the centre of the lamp.

With the aid of a diagram, outline how a polarity test can be conducted on a completed electrical installation before it is connected to an AC supply system.

State a function of EACH of the following semiconductor devices:

• Transistor
• Thermistor

Name TWO semiconductor materials.

Sketch the sinusoidal waveform for EACH of the following changing currents:

• Analogue
• Digital

Figure 5 shows the circuit diagram of a single stage transistor amplifier.

Explain the functions of EACH of the following pairs of components in the operation of the transistor amplifier:

R1 and R2

C1 and C2

R4 and C3

Figure 6 shows the schematic drawing of a bridge rectifier circuit.

Outline the operation of the rectifier circuit when it supplies d.c. to the load resistor, $R_L$.

Briefly describe the change in the operation of the bridge rectifier circuit when one of the four diodes is open-circuited.